Chemical Education Today
From Past Issues
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A Burning Issue by Kathryn R. Williams
“It would be hard to picture our present civilization without this efficient means of burning gas to produce heat.” This was Georg Lockemann’s assessment in “The Centenary of the Bunsen Burner”, an article that appeared in January 1956, to honor the 100th birthday of the Bunsen burner (1). His account describes the events surrounding development of what has become a laboratory necessity. In 1852, Robert Bunsen succeeded Leopold Gmelin as Professor of Chemistry at the University of Heidelberg. As part of his employment agreement, Bunsen stipulated the construction of a new laboratory building. His plans included piping for coal gas, a utility that was newly available in the city. Since the burners then in use produced smoky flames and gave low heat output, Bunsen undertook the task of designing an acceptable device. Two coworkers joined Bunsen in his endeavor: Henry Roscoe, a student, and Peter Desaga, the university’s instrument maker. Lockemann quotes Bunsen’s description from an 1857 paper with Roscoe (see Fig. 1), “If the tube…is screwed into the cylinder, and the city gas is allowed to flow into it…, it sucks in so much air through the openings d that it burns at the mouth of the tube e with a nonluminous, perfectly soot-free flame.” Bunsen did not intend to gain financially from the new design, so he never applied for a patent. As described by Moritz Kohn in an earlier article on burner history (2), a number of similar designs appeared in the mid-19th century. R. W. Elsner, a gas engineer from Berlin, was even able to obtain a patent for a burner almost identical to the Bunsen type (Fig. 2). In a later modification (Fig. 3), Alfred Terquem added a clamping device and divided the top opening into four quadrants.
Although we are reminded of Bunsen whenever we see a laboratory gas jet, the familiar burner illuminates only a tiny fraction of his accomplishments, including love of the classics, which he read in the original Latin, and a record of tireless teaching in both the lecture hall and the laboratory (3). The burner served as an essential tool in Bunsen’s research in photochemistry and his spectroscopic studies with Gustav Kirchhoff (Fig. 4). The portrait of Bunsen in Figure 5 appeared as the frontispiece Figure 1: Bunsen’s original dein the April 1927 issue of the sign. (Drawing provided by the Journal. That issue also conDeutsches Museum, Munich; it tains an eight-page biograappeared as Figure 1 in ref 1.) phy of Bunsen written by Ralph E. Oesper (3), who translated the Lockemann and Kohn papers a half-century later. Experienced lab workers will note that the design in Figure 1 lacks several features present in today’s student burners. To give more flexibility in the combustion mixture, a rotating perforated ring was added around the air intake holes later in the 19th century. In his paper, “Adaptation of the Bunsen Burner to Natural Gas” (4), G. Ross Robertson of UCLA describes later changes. It was Robertson’s article,
Figure 3. Alfred Terquem’s 1880 modification to the Bunsen burner. (Ref 2 (Kohn), Figure 4)
Figure 2. Sketches by Elsner: (A) burner; (B) burner with handle and stand; (C) and (D) multiple-burner heating arrangements. (Ref 2 (Kohn), Figure 2)
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Journal of Chemical Education • Vol. 77 No. 5 May 2000 • JChemEd.chem.wisc.edu
Chemical Education Today
From Past Issues
ing from the mouth of the stack and subsequent blowout. But in the 1930s, the “cost of manufacture of such a stack [was] too high for the economics of common student burners.” (4) The more economical design still familiar today (Fig. 6b) uses an overall increase in tube diameter (0.5 in. compared to 7/16 in. in the 19th-century version) with an extra sleeve at the top to retard the velocity of the fuel/air mixture and to stabilize the flame. I have to admit that, despite many years teaching flame spectroscopy, I was quite uninformed about burner design until I started work on this story. The four articles discussed briefly here are highly recommended reading, as are other hits from a search of JCE ’s online index with “burner” in the title field. For additional background, be sure to look at “Combustion and Flame” (5). In this resource paper, Robbin Anderson presents an annotated compilation of over 100 references on a variety of combustion-related topics, including flame structure and combustion reactions; theories of flame propagation; historical material; and instructional exercises.
Figure 5. Robert Bunsen, from the frontispiece of the April 1927 issue of the Journal.
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found on a fingerwalk through volume 9, that ignited my interest and further investigation of the subject and resulted in this article. By the early 1930s, the “widespread invasion of natural gas into American laboratories…[raised] a real chorus of complaints, audible in Chicago and Pittsburgh.” Coal gas, the fuel of Bunsen’s Heidelberg, contains over 50% hydrogen, which requires little air for combustion. “Accordingly Bunsen found no difficulty in providing adequate air intake facilities.” (4) Consisting primarily of lower alkanes and no hydrogen, natural and “cylinder” gases need a much faster air flow. In a Méker burner, the Venturi shape (Fig. 6a) increases air entrainment, and the gridded top prevents the flame from lift-
Supplemental Material
References 1 and 4 have been reproduced and are available in this issue of JCE Online. Literature Cited 1. 2. 3. 4. 5.
Lockemann, G. J. Chem. Educ. 1956, 33, 20–22. Kohn, M. J. Chem. Educ. 1950, 27, 514–516. Oesper, R. E. J. Chem. Educ. 1927, 4, 431–439. Robertson, G. R. J. Chem. Educ. 1932, 9, 1963–1969. Anderson, R. C. J. Chem. Educ. 1967, 44, 248–260.
Kathryn R. Williams teaches in the Department of Chemistry, University of Florida, PO Box 117200, Gainesville, FL 32611-7200,
[email protected].
Figure 4. Sketch of an early spectroscope provided by the Deutsches Museum, Munich. (Figure 3 in ref 1)
Figure 6: Stack modifications: (A) Venturi tube, left; (B) Tube with sleeve and baffle, right. (Figs. 2A and 2D in ref 4)
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